This invention relates to a multifunction signal switch suitable for use in a motor vehicle and, in particular, to a self-contained signal switch which is both rugged in construction and easy to maintain.
As exemplified by U.S. Pat. No. 3,858,176, multifunction switches such as turn signals and hazard warning devices are typically housed within the steering column of the vehicle. The size of the switch components is thus restricted and, as a consequence, the switch assemblies are susceptible to breakage when subjected to prolonged strenuous usage. The in-column switch assembly has therefore not found wide acceptance in heavy duty equipment. Similarly, it is difficult to perform maintenance upon a signal switch assembly that is built into the steering column because of the limited amount of space available in which to work. Normally, when such maintenance is required, the vehicle must be taken out of service for a period of time which, in the case of a heavy duty truck, can be costly.
To overcome some of the difficulties associated with the in-column signal switches, many heavy duty vehicle users have turned to the stronger and generally more reliable "hang on" or self-contained assemblies which can be clamped to the outside of the steering post. Although more accessible, these devices are still difficult to maintain because the electrical components, and particularly the switch contacts, are generally hard wired into the circuitry. Accordingly, changing contacts, which become worn with usage, require special maintenance that usually necessitates removal of the vehicle from service.
Most signal switch assemblies, whether self-contained or otherwise, only offer two modes of operation; a turn signal mode and a hazard warning mode. As a result, full advantage of the conveniently located signal switch is not truly realized.